1. Field of the Invention
The present invention relates to a dual flow inflator for injecting multiple gas flows of gas into an automobile airbag system. More specifically, the present invention relates to a dual flow injector structured to provide independently adjusted gas flows to selected portions of an inflatable airbag system, such as an inflatable curtain.
2. Description of Related Art
The inclusion of inflatable safety restraint devices, or airbags, is now a legal requirement for many new vehicles. Airbags are typically installed in the steering wheel and in the dashboard on the passenger side of a car. In the event of an accident, an accelerometer within the vehicle measures the abnormal deceleration and triggers the expulsion of rapidly expanding gases from an inflator. The expanding gases fill the airbags, which immediately inflate in front of the driver and passenger to protect them from impact against the windshield. Side impact airbags, known as inflatable curtains, have also been developed in response to the need for protection from impacts in a lateral direction, or against the side of the vehicle. An inflatable curtain may have one or more separately inflated inflatable curtains.
Side impact inflatable curtains are often designed to unfold or unroll downward to inflate beside a person to keep the person from hitting the door or window during lateral impact. Since a vehicle occupant may be leaning forward, reclined in the seat, or at any position between, such inflatable curtains are often made somewhat long to ensure that the occupant hits the inflatable curtain. If multiple inflatable curtains are fed by a single inflator positioned either fore or aft of the inflatable curtains, an especially long gas flow path exists between the inflator and the inflatable curtain furthest from the inflator. Thus, the outermost extents of the inflatable curtain may receive insufficient inflation gas pressure to inflate to the optimal protective pressure.
Even with somewhat shorter inflatable curtains, even and rapid inflation can be difficult to achieve with known inflator designs. Many existing inflators eject inflation gases outward radially; consequently, the inflation gases are not propelled along the length of the inflatable curtain, but are directed into the inflatable curtain near the inflator. The outer regions of the inflatable curtain are still inflated later than those closest to the inflator.
The problem of uneven gas distribution creates further design problems in the advanced and intelligent air bag deployment systems. Current automobile safety trends are leaning towards implementing multiple inflatable curtains along the sides of an automobile. These curtain airbag placement requirements may require varying sized and positioned inflatable curtains. Unfortunately, this presents the problem of simultaneously inflating two or more differently sized inflatable curtains at a single instant.
For example, inflatable curtain placement in a minivan may require two generally short inflatable curtains for the first two rows of seats and a third generally long inflatable curtain for the third row. The inflation of these differently sized inflatable curtains may require multiple inflators for each individual inflatable curtain. However, each inflator adds significant cost to the overall price of the automobile, causing some automobile manufacturers to decide against multiple side impact inflatable curtains.
While current innovations are addressing the problem of simultaneously inflating two similarly sized inflatable curtains, no technology is presently commercially available to inflate two differently sized inflatable curtains with a single inflator. Thus, present inflatable curtain systems are not capable of providing the controllability that may be obtained from an inflator having two independently controlled flows of gas.
Therefore, what is needed is an inflatable curtain inflator capable of simultaneously inflating two or more differently sized inflatable curtains. There is also a need for an inexpensive inflator capable of inflating multiple inflatable curtains. In that regard, there is a need for an inflator capable of inflating multiple inflatable curtains using a single initiator. It would be an advancement in the art to include these factors in a general small and thin inflatable curtain capable of being located along a roof rail. It would also be an advancement in the art to provide an inflator capable of producing two different mass flows of gas from a single inflator, such that a curtain system is capable of inflating two inflatable curtains with different internal gas pressures. It would be a further advancement to provide an inflator system that can be easily adjusted to inflate a wide range of inflatable curtain sizes. Such an inflator and system is described and claimed herein.